In grammar, the voice of a verb describes the relationship between the action (or state) that the verb expresses and the participants identified by its arguments (subject, object, etc.). When the subject is the agent or doer of the action, the verb is in the active voice. When the subject is the patient, target or undergoer of the action, the verb is said to be in the passive voice. Voice is sometimes called diathesis.[2]

For example, in the sentence:

The cat ate the mouse.

the verb "ate" is in the active voice. However, in the sentence:

The mouse was eaten by the cat.

the verbal phrase "was eaten" is passive.

In the sentence:

The hunter killed the bear.

the verb "killed" is in the active voice, and the doer of the action is the "hunter".
A passive version of the sentence is:

The bear was killed by the hunter.

where the verbal phrase "was killed" is followed by the word "by" and then by the doer "hunter".

In a transformation from an active-voice clause to an equivalent passive-voice construction, the subject and the direct object switch grammatical roles. The direct object gets promoted to subject, and the subject demoted to an (optional) adjunct. In the first example above, the mouse serves as the direct object in the active-voice version, but becomes the subject in the passive version. The subject of the active-voice version, the cat, becomes part of a prepositional phrase in the passive version of the sentence, and can be left out entirely.

In the grammar of Ancient Greek, voice was called διάθεσις (diáthesis) "arrangement" or "condition", with three subcategories: active (ἐνέργεια [enérgeia]), passive (πάθος [páthos]), and middle (μεσότης [mesótēs]).[3][4]
In Latin there are two voices: active and passive (Latin: [genus] activum, passivum).

The passive voice is employed in a clause whose subject expresses the theme or patient of the verb. That is, it undergoes an action or has its state changed.[5]

In the passive voice the grammatical subject of the verb is the recipient (not the doer) of the action denoted by the verb.

Some languages, such as English and Spanish, use a periphrastic passive voice; that is, it is not a single word form, but rather a construction making use of other word forms. Specifically, it is made up of a form of the auxiliary verbto be and a past participle of the main verb. In other languages, such as Latin, the passive voice is simply marked on the verb by inflection: librum legit "He reads the book"; liber legitur "The book is read".

Some languages (such as Albanian, Bengali, Fula, Tamil, Sanskrit, Icelandic, Swedish, Biblical Hebrew and Ancient Greek) have a middle voice, which is a set of inflections or constructions which is to some extent different from both the active and passive voices. The middle voice is said to be in the middle between the active and the passive voices because the subject often cannot be categorized as either agent or patient but may have elements of both. For example, it may express what would be an intransitive verb in English. In The casserole cooked in the oven, cooked is syntactically active but semantically passive. In Classical Greek, the middle voice often has a reflexive sense: the subject acts on or for itself, such as "The boy washes himself", or "The boy washes". It can be transitive or intransitive. It can occasionally be used in a causative sense, such as "The father causes his son to be set free", or "The father ransoms his son".

In English there is no verb form for the middle voice, though some uses may be classified by traditional grammarians as middle voice, often resolved via a reflexive pronoun, as in "Fred shaved", which may be expanded to "Fred shaved himself" – contrast with active "Fred shaved John" or passive "John was shaved by Fred". This need not be reflexive, as in "my clothes soaked in detergent overnight". English used to have a distinct form, called the passival, which was displaced over the early 19th century by the progressive passive and is no longer used in English.[6][7] In the passival, one might say "The house is building.", which may today be rendered instead as "The house is being built." Likewise "The meal is eating.", which is now "The meal is being eaten." Note that the similar "Fred is shaving" and "the clothes are soaking" remain grammatical. It is suggested that the progressive passive was popularized by the Romantic poets, and is connected with Bristol usage.[6][8]

Some languages have even more grammatical voices. For example, Classical Mongolian features five voices: active, passive, causative, reciprocal, and cooperative. Hebrew has active, passive, causative, intensive and reflexive voices.

There are also constructions in some languages that appear to change the valence of a verb, but in fact do not. So called hierarchical or inversion languages are of this sort. Their agreement system will be sensitive to an external person or animacy hierarchy (or a combination of both): 1 > 2 > 3 or Anim > Inan and so forth. E.g., in Meskwaki (an Algonquian language), verbs inflect for both subject and object, but agreement markers do not have inherent values for these. Rather, a third marker, the direct or inverse marker, indicates the proper interpretation: ne-wa:pam-e:-w-a [1-look.at-DIR-3-3Sg] "I am looking at him", but ne-wa:pam-ekw-w-a [1-look.at-INV-3-3Sg] "He is looking at me". Some scholars (notably Rhodes) have analyzed this as a kind of obligatory passivization dependent on animacy, while others have claimed it is not a voice at all, but rather see inversion as another type of alignment, parallel to nominative–accusative, ergative–absolutive, split-S, and fluid-S alignments.

Topic-prominent languages like Mandarin tend not to employ the passive voice as frequently. Mandarin-speakers construct the passive voice by using the coverb被 (bèi) and rearranging the usual word order.[10] For example, this sentence using active voice:

Note: the first line is in Traditional Chinese while the second is Simplified Chinese.

狗

狗

Gǒu

dog

咬了

咬了

yǎo-le

bite-PERFECT

這個

这个

zhège

this

男人。

男人。

nánrén.

man

狗 咬了 這個 男人。

狗 咬了 这个 男人。

Gǒu yǎo-le zhège nánrén.

dog bite-PERFECT this man

"A dog has bitten this man."

corresponds to the following sentence using passive voice. Note that the agent phrase is optional.

這個

这个

Zhège

This

男人

男人

nánrén

man

被

被

bèi

PASSIVE

(狗)

(狗)

(gǒu)

dog

咬了。

咬了。

yǎo-le.

bite-PERFECT

這個 男人 被 (狗) 咬了。

这个 男人 被 (狗) 咬了。

Zhège nánrén bèi (gǒu) yǎo-le.

This man PASSIVE dog bite-PERFECT

"This man has been bitten (by a dog)."

In addition, through the addition of the auxiliary verb "to be" (shì) the passive voice is frequently used to emphasize the identity of the actor. This example places emphasis on the dog, presumably as opposed to some other animal:

這個

这个

Zhège

This

男人

男人

nánrén

man

是

是

shì

to be

被

被

bèi

PASSIVE

狗

狗

gǒu

dog

咬了。

咬了。

yǎo-le.

bite-PERFECT

這個 男人 是 被 狗 咬了。

这个 男人 是 被 狗 咬了。

Zhège nánrén shì bèi gǒu yǎo-le.

This man {to be} PASSIVE dog bite-PERFECT

"This man has been bitten by a dog."

Mandarin has also a object-retaining passive which contains both object and topic (mostly the possessor of the object) :

In the actor-emphasizing passive voice of Cantonese, besides the addition of the auxiliary verb "to be" (hai6) , the perfective event is also converted to a adjective-like predicative with the suffix 嘅(ge3) or㗎(gaa3), which is a more emphasized one from the liaison of 嘅(ge3) and 啊(aa3):

Although a topic-prominent language, Japanese employs the passive voice quite frequently, and has two types of passive voice, one that corresponds to that in English and an indirect passive not found in English. This indirect passive is used when something undesirable happens to the speaker.

Some languages do not contrast voices, but have other similar constructions. For example, Finnic languages such as Finnish and Estonian have a "passive", expressed by conjugating the verb in "common person". Although it is generally referred to as the passive ("passiivi") in Finnish grammars, it may more appropriately be referred to as the fourth person form of a verb.

Similarly in French and Welsh, impersonal forms are used: On lit le journal.; Darllenir y papur newydd.: "One reads the newspaper.", i.e., "The newspaper is read."

The function of the fourth person is simply to leave out the agent. The agent is almost always human and never mentioned. The grammatical role of the object remains unaltered, and thus transitivity may also be used. For example, the fourth-person construction Ikkuna hajotettiin, with a transitive verb, means "Someone broke the window", while the third-person construction Ikkuna hajosi uses the anticausative and means "The window broke".

Celtic languages have an inflection commonly called the "impersonal" or "autonomous" form,[11] of similar origin[citation needed] to the Latin "passive-impersonal". This is similar to a passive construction in that the agent of the verb is not specified. However its syntax is different from prototypical passives, in that the object of the action remains in the accusative.[12]

It is similar to the use of the pronoun "on" in French (except wherever "on" is instead used an alternative to "we", which is very frequent). It increasingly corresponds to the passive in modern English, in which there is a trend towards avoiding the use of the passive unless it is specifically required to omit the subject. It also appears to be similar to the "fourth person" mentioned in the preceding paragraph. However, what is called in Irish an briathar saor or the free verb does not suggest passivity but a kind of generalised agency.

The construction has equal validity in transitive and intransitive clauses, and the best translation into English is normally by using the "dummy" subjects "they", "one", or impersonal "you". For example, the common sign against tobacco consumption has its closest direct translation in English as "No smoking":

Ná

Don't

caitear

use-IMPERSONAL

tabac

tobacco.

Ná caitear tabac

Don't use-IMPERSONAL tobacco.

An example of its use as an intransitive is:

Téithear

Go-IMPERSONAL

go dtí

to

an sráidbhaile

the village

go minic

often

Dé Sathairn

Saturday

Téithear {go dtí} {an sráidbhaile} {go minic} {Dé Sathairn}

Go-IMPERSONAL to {the village} often Saturday

"People often go to the village of a Saturday."

The difference between the autonomous and a true passive is that while the autonomous focuses on the action and overtly avoids mentioning the actor, there is nonetheless an anonymous agent who may be referred to in the sentence. For instance:[13]

Théití

go[PAST.HAB.AUT]

ag

eat

ithe

PROG

béile

meal

le chéile

with each other

Théití ag ithe béile {le chéile}

go[PAST.HAB.AUT] eat PROG meal {with each other}

"People used to go eating a meal together."

In English, the formation of the passive allows the optional inclusion of an agent in a prepositional phrase, "by the man", etc. Where English would leave out the noun phrase, Irish uses the autonomous; where English includes the noun phrase, Irish uses its periphrastic passive – which can also leave out the noun phrase:

The

Bhí

Was

tobacco

an

the

was

tabac

tobacco

smoked

caite

consumed

(by

(ag

(by

the

an

the

man)

bhfear)

man)

The tobacco was smoked (by the man)

Bhí an tabac caite (ag an bhfear)

Was the tobacco consumed (by the man)

The impersonal endings have been re-analysed as a passive voice in Modern Welsh and the agent can be included after the preposition gan (by):

Some linguists draw a distinction between static (or stative) passive voice and dynamic (or eventive) passive voice in some languages. Examples include English, German, Swedish, Spanish and Italian. "Static" means that an action was done to the subject at a certain point in time resulting in a state in the time focussed upon, whereas "dynamic" means that an action takes place.

In Venetian (Vèneto) the difference between dynamic (true) passive and stative (adjectival) passive is more clear cut, using èser (to be) only for the static passives and vegner (to become, to come) only for the dynamic passive:

Ła porta ła vien verta. "The door is opened", dynamic

Ła porta ła xè / l'è verta. "The door is open", static

Static forms represents much more a property or general condition, whereas the dynamic form is a real passive action entailing "by someone":

èser proteto. "To be protected = to be in a safe condition", static

vegner proteto. "To be protected = to be defended (by so)", dynamic

èser considarà. "To be considered = to have a (good) reputation", static

vegner considarà. "To be taken into consideration (by people, by so)", dynamic

èser raprexentà (a l'ONU). "To be represented (at the UN) = to have a representation", static